1. Field of the Invention
The present invention generally relates to a detection apparatus for plasma process, and more particularly, to a detachable detection window and detecting system.
2. Description of Related Art
Currently, integrated circuit (IC) manufacturers have broadly employ plasma technology for carrying out various semiconductor processes, such as deposition of film, etching of film or stripping of photoresist layer. For example, a film deposition may be able to reduce the thermal budget of the process to reduce the fabrication cost. In additionally, an etching of film using the plasma technology can provide a non-isotropic etching process.
Usually, one of problems occurring during the fabrication of wafers in a semiconductor equipment with a plasma chamber is that it is hard to detect whether the plasma has been triggered or ensure the fabrication situation of wafer in the plasma chamber. Thus, it would be highly desirable to equip the plasma chamber with a detecting system to precisely detect the situation in the plasma chamber.
FIG. 1 is a view showing a conventional detection window used in a plasma machine. The detection window 100 in FIG. 1 is one having been used for a certain time already. The detection window 100 is comprised of quartz and has a shape of a barrel container having a base disposed at the bottom portion thereof. Since the detection window 100 is an integrally formed structure formed by using a sintering process; thus, an uneven surface are formed at the bottom portion thereof (an area indicated by the arrow 102), which causes a poor optical transmittance. Other problems associated with the detection window 100 include difficulty to clean detection window 100 and to thoroughly clean the detection window 100. In order to resolve the above-mentioned problems, a chemical solution was proposed, which not only increases the cost, but also corrodes the detection window 100 and also cause chemical traces contamination. When conducting a periodic preventive maintenance (PM) on a machine, it is always found that the detection window is corroded by plasma gas may cause damage or atomization problem. Therefore, after a period of usage, the detection window 100 must be replaced with a new one, which significantly increases the cost.
In addition to the increasing cost, the above-mentioned problems due to uneven bottom surface, chemical trace, corrosion and atomization may cause a misjudgment of an end point detection during a wafer etching process, which would seriously affect the reliability of the process.